s3api: add error code and header constants for GetObjectAttributes

Add ErrInvalidAttributeName error code and header constants
(X-Amz-Object-Attributes, X-Amz-Max-Parts, X-Amz-Part-Number-Marker,
X-Amz-Delete-Marker) needed by the S3 GetObjectAttributes API.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

weed/s3api/s3err/s3api_errors.go

@@ -143,6 +143,8 @@ const (
 	// Bucket encryption errors
 	ErrNoSuchBucketEncryptionConfiguration
 	ErrInvalidStorageClass
+
+	ErrInvalidAttributeName
 )
 
 // Error message constants for checksum validation
@@ -600,6 +602,12 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "The storage class you specified is not valid",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+
+	ErrInvalidAttributeName: {
+		Code:           "InvalidArgument",
+		Description:    "Invalid attribute name specified",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 }
 
 // GetAPIError provides API Error for input API error code.